Machine tool



fhg. s, 1946. QH. SCHURR' f 2,405,522

MACHINE TOOL Filed April l. 1942 7 Sheets-Sheet 1 Hfs ATTQHNEYS.

A|l8- 5, 1946- l i c. H. scHuRR 1 2,405,522

MACHINE' TOOL Filed `April l, 1942 t '7.Sheets-Sheet 2 Fis. 5

NVETOR:

Hfs ArronNsvs.

Aug 6 1946. v c. H. scHuRR -24055j22 MACHINE TOOL Filed April 1, 1942 7 sheets-sheet :s

@Vm/M+ -H/s ATTORNEYS.

c. H. sca-MRR 2,405,52

MACHINE TOOL Filed April 1, 1942 '1 sheets-shew 4 @mam Aug. 6, '1946. c. H. scHuRR MACHINE 'TOOL Filed April l. 1942 '7 sheen-sheet 5 n 70E/VE,

CALH. SCHURR MACHINE TOOL I Filed April l, 1942 '7 Sheets-Sheet 6 .HA/S A TTOENEYS Patented Aug. 6, `1946 MACHINE TOOL Charles H. Schurr, Cleveland, Ohio, assigner to The Lees-Bradner Company, a corporation of Ohio Cleveland, Ohio,

Application April 1, 1942, Serial No. 437,112

17 Claims. 1

This invention relates to a machine tool, and particularly to a tool which is adapted to the accurate forming of surfaces .on metal and like materials.

An object of the invention is to provide an improved machine tool -which will form non-cylindrical surfaces with extreme accuracy.

Another object is to provide an improved machine tool which will be of simple and rugged construction.

Another object is to provide an improved machine tool which will require relatively few moving parts.

Another object is to provide an improved machine tool which will have extremely little back lash or looseness.

Another object isto provide .an improved machine tool which will occupy relatively small iioorl space. ,i

Another object is to provide an improved 1nachine tool which will ybe neat and compact.

Another object is to provide an improved machine tool which may be easily operated.

Another object is to provide an improved machine tool which may be quickly and easily adjusted to accommodate itself to performing different operations.

Another object is to provide an improved machine tool which maybe readily and economically manufactured.

Another object is to provide an improved machine tool which shall be both quick and eiilcient in its operation. i

Other objects will hereinafter appear.

The invention will be better understood from the description of one practical embodiment thereof, illustrated in the accompanying drawings, in lwhich:

Figure 1 is a front elevational view of a machine tool, the type chosen for illustration being that commonly called a thread milling machine, embodying the invention, parts of the base being broken away;

Figure 2 is a transverse fragmentary sectional View taken on the line II-II of Figuije 1;

Figure 3 is apartially elevational and partially transverse view taken on the line'III-III of Figure 1;

Figure 4 isa longitudinal sectional view taken on the line IV-IV of Figure 3;

Figure 5 is a iragmentaryisectional on the line V-V of Figure 3;

Figure 6 is a fragmentary sectional view taken on the line VI-VI of Figure 3.;

Figure 'l is a plan View of a machinel to 'a smaller View taken scale than `that to which the parts are shown in the preceding lgures;

Figure 8 lis an enlarged fragmentary cross sectional view of the automatic feeding device taken on the line VIII-VIII of Figure 4;

Figure 9 is a fragmentary sectional view taken on the line IX-IX'of Figure 3;

Figure 10 is a fragmentary sectional view taken on the line X-X of Figure 3;

Figure 11 is a diagrammatic view of the various driving connections ofthe apparatus of the preceding figures; and

Figure 12 is a diagrammatic illustration of the electric circuits involved.

Figure 13 'is a View partly in plan and partly in section, taken on the line XIII-XIII of Figure 1; and

Figure 14 is an elevational View, partly in section, taken on the line XIV-XIV of Figure 13.

In Figure 1, the machine is shown as having a supporting base or pedestal I, this conveniently being,as shown, a hollow casting opening toward its bottom and having spaced top walls 2 and 3 and transverse websor walls 4, 5, 5, 1 and 8, and front and 'back walls 9 and I0.

Upon the upper surfaces of the top walls 2 and y3y are formed, integrally therewith, longitudinally extending Ways I I and I2.

Extending along the front, rear, vand one end of the base is a trough I3, formed integrally therewith, whichfopens into a central depressed space between walls 6 and 1, these walls being provided with horizontal lianges I4 and l5 upon which a rectangular container IB is supported for the reception of chips, this container being movable like a drawer into and out of the space between'the walls 6 and 'I for convenience in 'removal of the chips.

Mounted upon the ways II and I2 are a work head and a cutter head.

The latter is shown to the right in Figures 1 and 4, and consists of a supporting bracket indicated generally at I'Iprovided with bearings I8 and I9 in which is supported, with its axis generally parallel to the ways, a tool spindle 20.

The end .of the tool spindle projects at 2| beyond the end 0f the base and is provided with a pulley 22 keyed to it and held upon the tapered end 2| of the spindle as by a nut 213, this pulley being shown as grooved for the use of a double V-belt 24.

The belt is driven from a pulley 25 fixed to the shaft of a motor 26 located within the space in the base'dened by walls 'l and 8,'top 3, and between fr'ont 9 and back 1U.

retain lubricant in the bearings, and prevent the entry of chips, dirt, and the like.

Journalled in the cutter head is a transverse shaft 3l provided on itsI outer endwith a hand wheel 32 and having keyed to it a skew gear 3 This meshes with a skew gear 34 keyed to a lead screw 35 which extends lengthwise of the machine to substantially the remote (or left hand) end of the bed. The lead screw is prevented from axial movement by thrust bearings 38.

The work head is shown to the left in Figures l and 4, and includes a carriage 31 slidable upon ways Il and l2.v The carriage hasa depending boss 38 in which is secured a nut 39, engaging the threads 48 of the leadscrew 35, by which the carriage may be moved upon its ways.

A locking screw and handle 4| are provided for clamping the carriage at any desired adjusted position. K

The upper surface of the carriage is formed with transverse-,ways slidably mounted a'transversely movable slide 44 having a'flat upper surface provided with a central circular depression 45.

The lower surface of the slide has a depending boss 48; movable in the space between the ways 42 and 43, provided with a nut 41 engaging the threads of a screw 48 for moving the slide upon the carriage,

L'I'he operation of this screw will be described more fully hereinafter. K

Upon the upper surface of the slide is a frame 49 having a circular plate 5i) attached to it, this vfitting closely within the recess 45 so that the frame Ymay be angularly adjusted with respect to Vthe slide. This adjustment is permitted by machine screws 51 threaded into the slide and extending through arcuate slots in the lower portion of the frame 49.

The frame carries spaced bearings 52 and 53A, in which is rotatably and slidably mounted a hollow work spindle 54. This spindle on .its end adjacent the cutter head has an outwardly extending iiange 55 which limit-s its axial motion inone direction.

At the other end the work spindle has keyed to it a removable externally threaded ring 55 held in place by an internally threaded ring or nut 51.

Theexternal thread of ring 58 is engaged by a conjugate thread cut into a segmental shoe 58' detachably secured to the frame by screws 59.

Also keyed to the exterior ofthe spindle 54 is a gear 88, held in place by an internally threaded ring or nut'8l, which gear meshes with a worm 82 formed integrally with a transversely extending shaft'53.

This shaft is supported at its forward end in bearings 54 carried by the frame, the end of the shaft projecting through a cap 85 and being squared, as indicated at t5, for the application of a wrench or the like in effecting adjustments.

Shaft 83 is journalled at 51 within the frame and has splined to it a clutch member 68. This clutch member is provided on one end with a jaw clutch element 69 engageable with a corresponding jaw element fixed to a skew gear 18.

AThe other end of clutch member 68 is arranged to cooperate'with a disc friction clutchfil, by which the shaft 83 may beconnected with a shaft 42 and 43, upon which is 12 in axial alignment therewith and provided with a skew gear 13.

The clutch member 88 may be moved in either direction by a yoke 14 carried by a vertical shaft which extends upwardly through the top of the frame and is provided on its outer end with a hand lever 16.

On the rear part of the frame is hinged at 11 a bracket 18 carrying a motor 19, the shaft oi which is provided with a pulley 88 over which pass V-belts 8l to a pulley 82 fixed to a longitudinally extending shaft 83.

This shaft has secured to it a skew gear 84 meshing with skew gear 13, and at its outer end detachably connected to it one of a series of change gears 85 which drives, through an idler gear 86, another change gear 81 detachably secured to the shaft 88 which in turn has formed upon it a worm 89, the latter meshing with worm wheel 10. 'j

Thus, it will be apparent that the work spindle may be driven at either of two speeds, controlled by the position of lever 18.

If the jaw clutch 89 is engaged, the drive is from motor 19 through pulley 88, belts 8|, pulley 82, shaft 83, change gears 85, 88, and 81 to shaft 88, thence through worm 89 to worm wheel 1E] which is now clutched to the shaft 63 and so in turn drives the worm 62, rotating the gear and with it the spindle at a speed suitable for cutting.

As the spindle rotates, the threaded ring 58, traveling upon the fixed shoe 58 moves the spindle axially by an amount determined by the lead of the threads of parts 58 and 58. If a different axial feed is desired, these two parts may be readily replaced by others having the proper lead.

If, however, the lever 16 is moved in the opposite direction, it disengages jaw clutch t9- and engages friction clutch 1I. Now power is transmitted from shaft 83 through skew gears 84 and 13 to shaft 12, through clutch 1l to shaft 53, and it will be apparent that the latter now is driven at a substantially higher rate of speed than when the jaw clutch is engaged.

It also is driven preferably in a reverse direction, thus providing a quick return, moving the spindle to its initial position.

In practice, a spring is provided for rotating shaft 15 in the direction to engage the jaw clutch elements 89, so that the operator may move the lever into position to engage the friction clutch 1|, and, when the return motion has been completed, merely releases the lever, whereupon the spring will cause the engagement of the jaw clutch elements 89, so that he need not hold these elements engaged while the cutis being performed.

A brake 98 is provided on a shaft 83, this being electrically controlled to stop the parts, as will be more fully described hereinafter.

The forward end of screw 48 is journalled in the carriage 31 as indicated at 9|, the screw having a shoulder which abuts the journal and so limits its outward movement.

Beyond the journal the screw shankA is sur roundedby a compression spring 92 bearing at one end against a collar 93 secured to screw 48 and at its` other end against a flange 94 formed within a sleeve 95, the other side of this flange bearing upon a thrust bearing 95, which, in turn, abuts the journal 9i.'

The outer end of the screw is squared as indicated at 91 for the reception of a hand wheel, crank,` or the like, byfwhich thescrew may be Fixed to the cam is a worm wheel |92 meshing with the worm |63 upon a shaft 6d.

To the outer end of the shaft is attached a change gear I |35' meshing with a change gear |66 detachably ixed to a short horizontal shaft |01, the inner end of which is provided with a worm wheel |68 driven by the worm |09 formed in the shaft of a motor I||.

Fixed to the other end of the motor shaft is a brake I I2. v

The functioning of these parts will more fully appear from the description of the operation of the machine.

It will be noted that the motor 2% is mounted upon -a plate H3, pivoted at |||i within the base, and having supporting screws H5 threaded through its free end, whereby the amount of weight imposedupon belts 2d may be adjusted to maintain these belts at any desired tension.

The recess between walls 6 and 1 terminates at a nearly horizontal bottom wall IIS which permits coolant lluid to iiow down into a sump ||l formed in the rear of the base.

A cam is i'lxed to Shaft 15, and two switches |2| and |22 are arranged to be valternately actuated by this cam as the lever 16 is moved from one side to the other.

The external surface of cam 99 is formed into an additional cam surface contacting the Vend of a horizontal rod |23 provided with two adjustable conical collars |2| and |25 which are respectively arranged to actuate switches |25 and |21 in accordance with the rotation of cam 99.

A forked follower I28'embraces the gear Sii, this follower being xed to a rod |29 provided with two conical collars |36 and ISI, thesebeing positioned to `actuate switches |32 and |33, respectively.

Thus, it will be seen that the switches |2I and |22 are controlled by the position of the lever 1d; |26 and |21 are controlled by the position of cam 99, and, consequently, in accordance with the position of the slide upon the carriage and switches |32 and |33 are controlled by the axial movement of the spindle in its bearings.

The switches and motor are connected as indicated in Figure 12.

Current is supplied from a power line or generator through conductors |34, |35 and |36, passing through a magnetic switch |31 to conductors I 38, |39 and ld, which connect, through a manually operable reversing switch indicated generally at I4I, with conductors M2, |43 and IM, respectively, connected to the motor 26.

Also connected to the switch |31 are conductors |45, IME and |41 connected to motor H9, so that whenever the magnetic switch |31 is closed the motor HS operates, supplying coolant to the cutter.

Connected to one terminal or" line |315 is a conductor |63 which extends to a normally open starting push button M9, the other side of this button being connected by a conductor |53 to a contact of a normally closed stopping push button |5I, and from this same contact of the second push button a conductor |52 passes to the switch |31. From the other side of stop button -I'5I current may pass through a thermal overload circuit breaker |53, to the coil |54 -con` trolling the magnetic switch |31, the circuit continuing through conductor 55, a second thermal overload switch I 56, and a conductor |51, back tothe end of line |36. y

rihus, it will be seen that when starting push button It@ is depressed to'complete the circuit, current flows through switch M9, conductor 15H3, push button I 5| thermal overload circuit breaker |53, solenoid |5fi, conductor |55, thermal overload switch i, conductor |51, back to the main line conductor |3, closing the contacts of the magnetic switch |31, and energizing conductors |38, i3@ and Mil to operate motor 26. The closing of the magnetic switch also connects line Hill with conductor |52 in parallel with start button M9 and acting as a hold in when the butto-n is released.V

When it is desired to stop the motor 26, the push button |5| may be actuated, breaking the circuit and discontinuing the currrent to the coil i5@ and so permitting switch |51 to open.

Connected to the opposite Contact of switch |5| from conductor |52 is a conductor |53, one end of which is connected. to switch |22. It is provided with a branch conductor |59 having its end connected to switch |25 and having another branch conductor me connected to switch |33.

It will be noted that conductor |53 may b-e energized by closing the starting switch MQ and is de-energized simultaneously with coil ii by the opening of switch 55|, so that the start and stop switches control all the circuits supplied by current through conductor |58.

From the other terminal of switch |22, a conductor |e| extends to one terminal switch |32, and from another contact of this latter switch a conductor |62 is connected to a conductor |63 having one end connected to a terminal of switch |2| and its other end connected to a terminal switch |21.

From the third terminal of switch |32 a conductor Hill extends, being attached to a conductor |55, one end of which connected to the other terminal of switch itl', and the other end of Ywhich passes through a thermal overload switch |56, the coil |i1 of a magnetic switch |58, a thermal overload switch |69, and a conductor |10, which is` connected to one end of line I1|, the other end of which is connected to line |35.

Lines |12 and |13 connect, respectively, lines |35 and |34 with the magnetic switch |65, and through the magnetic switch to conductors Hd, |15 and |15 connected to the motor Branch conductors |11 and |13 connected, respectively, to conductors |1|| and |16, extend to the ends of the coil |19 of the magnetic brake H2.

A conductor l@ connects the second end of switch |2$ with line H53.

A conductor I 8| connects the second contact of switch |2| with the second contact of switch |33. l

A conductor |82 extends from a third contact of switch |2| to a thermal overload relay |83, thence to the coil |86 of a magnetic switch |85, a second thermal relay iii, anda conductor |81 connected with one terminal of line it, the other end of which is connected to line i3d.l

Lines |89 and No connect, respectively, lines |35 and |34 with the magnetic switch i, `while lines |9I, |92 and ISS connect the corresponding terminals of this switch through a manual reversing switch |94 to the terminals of motor 19.

Branch conductors |95 and |95 connected, respectively, to conductors |9| and |93, are con# nected to the ends of the coil |91 of magnetic brake 96. Y

` Thus, it will be apparent that current is supplied to motors 19 and only after the actuation of the starting switch |49, and that such current is discontinued by the actuation of the stopping switch It will also be apparent that coils |19 and |91 are energized to retain their respective brakes ||2 and 96 in inoperative position only while the motors 19 and are operating.

The operation of the device is as follows: The operator presses the start push button |49 which permits current to flow through the magnet |54 of switch |31, closing this switch and supplying current to motors 26 and ||9.

It simultaneously supplies current to line |58.

After inserting a piece of work in the chuck |98 and clamping it by rotating hand wheel |99, the operator moves lever 16 to his left, closing switch |22 and permitting switch i2| to establish v a connection between conductors |8| and |82.

At this point of the operation, switch |33 is closed, so that current may flow through conductors |59 and |66, switch |33, conductor |8i, switch |2| and conductor |82 to energize the coil |84 of magnetic switch |85, starting the inotor 19.

Simultaneously, current passes through switch |22 and thence through conductor |6| to switch |32, then through conductors |62 and |63 to switch |21 and through this switch to conductor |65 connected to coil |61 of magnetic switch |68, closing this switch t0- energize motor which retracts the cutter from depth so that it will clear the work during its return to its starting position.

As the motor rotates to retract the cutter, cam 99 rotates, moving rod |23 to the left, as seen in Figure 12, so that when the cutter is fully retracted the cam will cause contact to open switch |21 and contact |24 to close switch |26.

The opening of switch |21 breaks the circuit between conductors |63 and |65 and stops the motor Motor 19 continuesV to operate, moving the spindle to the left and carrying with it contacts |38 and |3|.

When the spindle has reached its extreme position, these contacts will have moved switch |32 to-establish the circuit between conductors |62 and |64, and have reopened switch |33, thus breaking the circuit between conductors |66 and |8| and discontinuing current through the latter to switch 2|, conductor |82, and coil |84 of magnetic switch |85, thus causing this magnetic switch to open and stop motor 19.

The operator then releases lever 16, and its spring swings this lever to his right. This motion opens switch |22 and establishes .the circuit between conductors |63 and |82.

Current now ows through conductor |59, switch |26, conductor |80, conductor |63, switch |2|, and conductor |82 to coil |84 of magnetic switch |85, again closing this switch and causing the motor 19 again to operate.

The operators action in releasing the lever and the rotation of this lever and its, shaft have caused the yoke 14 to disengage the quick return clutch 1| and lto engage the cutting clutch 69, so that the spindle is now driven in the opposite or cutting direction and 'at a lower rate of speed than was the case when the lever was retained by the operator to his left.

.The release Of 'the lever, ofcourse' opens switch |22 but this does not effect the operation, inasmuch as the circuit controlled thereby has been broken at switch |32. Y

The actuation of switch |32 has now established a circuit between conductors |62A and |64, thence through conductor |65 to coil |61 of magnetic switch |68, again closing this switch and energizing motor to feed the cutter in to depth, this motion, of course, being likewise imparted to the cam 89 and moving abutments |24 and |25 .to the right, as seen in Figure 12. At the extreme position of these abutments, they open switch |26 and close switch |21.

The opening of switch |26 breaks .the circuit between conductors |59 and |63, .discontinuing the current to both coils |61 and |84, and stopping both motors and 19, at which time the parts have progressed to their positions atthe iinish of the cut, and it is time for the operator to replace the work piece with a fresh one.

It will :be notedthat neither of .the feed motors 19 and can be operated until the cutter motor 26 has been started, thus insuring that the operator will not start the piece rst and force the cutter and work into each other beforethe cutter is rotated.

While I have described the illustrated embodiment of my invention in some particularity, obviously many others will readily occur to those skilled in this art, and I do not, therefore, limit myself to the precise details shown and described, but claim as my invention all embodiments, variations, and modifications thereof coming within the scope of the appended claims.

I claim: Y Y

1. A machine tool comprising a tool holder, a rotatable work spindle, means for rotating said spindle, the tool holder and spindle being relatively adjustable axially, radially, and angularly, an externally threaded ring detachably secured to the spindle, a segment having a thread conjugate to the thread on said ring, and detachable securing means fixing said segment relative the tool holder, the threads of the segment and ring being in engagement.

2. A machine tool comprising two independently rotatable spindles, driving means connected to one of said spindles, separate driving means connected to the other spindle, feed means capable of relatively moving the spindles actuated by said second driving means, disengageable positive power transmission mechanism between the second mentioned driving means and the second mentioned spindle, a second disengageable power transmissionmechanism capable of transmitting motion at a dinerent rate of speed between the second mentioned driving means and the second mentioned spindle, and means for selectively alternately engaging said power transmission mechanisms.

3. A machine tool comprising two independently rotatable spindles, driving means connected to one of said spindles, separate driving means connected to the other spindle, feed means capable of relatively moving the spindles actuated by said second driving means, disengageable positive power transmission mechanism between the second mentioned driving means and the second mentioned spindle, a second disengageable power transmission mechanism capable of transmitting motion at a different rate of speed between the second mentioned driving means and the second mentioned spindle, and means for selectively a1- ternately engaging said power .transmission i9 mechanisms, a second` feed means capable of moving the spindles relatively'in a different direction, and means controlling said second mentioned feed means in accordance with the operation of said power transmission mechanisms.

4; A'machine tool, comprising a rotatable spindle, driving means therefor, two power transmitting mechanisms between said driving means and said spindle arranged to rotate the spindle at different speeds relative to that of the driving means, clutch means for selective alternate engaging either of said transmissionV mechanisms, feed means actuated in accordance with the rotation of the spindle, a second feed means, interconnections between said clutch means and said second feed means causing the latter to operate in vpredetermined relation to the operation of the power transmitting mechanisms.

5. A machine tool comprising two spindles, a motor arranged to drive one of said spindles, a second motor arranged to drive the other of said spindles, two power transmission mechanisms interposed between said last mentioned motor and spindle capable of driving the spindle at different speeds relative the speed of its motor, clutch means for selectively engaging either of said power transmission mechanisms, a feed means, a third motor connected thereto, control means for the third motor actuated in accordance with the clutch means, and control means fo-r the second and third motors actuated in accordance with the operation of the first mentioned motor.

6. A machine tool comprising two spindles, a motor arranged to drive one of said spindles, a second motor arranged to drive the other of said spindles, two power transmission mechanisms interposed between said last mentioned motor and spindle capable of driving the spindle at different speeds relative the speed of its motor, clutch means for selectively engaging either of said power transmission mechanisms, feed means operating in accordance with the rotation of said second mentioned spindle, control means actuated by .said feed means, said control means controlling the second mentioned motor, a second feed means, a third motor connected thereto, control means for the third motor actuated in accordance with the clutch means, and control means for the second and third motors actuated in accordance with the operation of the rst mentioned motor.

A machine tool comprising a base, stationary bearings carried thereby, a spindle rotatably supported by said bearings, ways upon the base extending in the direction of the axis of the spindle, a carriage slidable upon said ways, slide mounted on the carriage and movable in 'a direction transverse to said ways, bearings carried by the slide, a spindle rotatably and slidably-carried by said bearings, means for driving said spindles, a feeding element carried by said second mentioned spindle, a corresponding feeding element in engagement therewith and fixed with` respect to said bearings, means for moving the slide on the carriage, and means for moving the carriage on the base.

8. A machine tool comprising a base, stationary bearings carried thereby, a spindle rotatably supported by said bearings, ways upon the Ibase extending in the direction of the axis of the spindle, a carriage slidable upon said ways, a slide mounted on the carriage and movable in a direction transverse to said ways, bearings carried by the slide and angularly adjustable with respect to the motions of the carriage and slide, a spindle rotatably and slidably carried by said bearings,

10 means for driving said spindles, a feeding element carried by said second mentioned spindle, a corresponding feeding element in engagement therewith and fixed with respect to said bearings, means for moving the slide on the carriage, and means for moving the carriage on the base.

9. A machine tool comprising a rotatable and axially translatable spindle, driving means therefor, power transmission mechanism interposed between the driving means and the spindle comprising two gear trains, a jaw clutch between one lof said gear trains and the spindle, and a friction clutch between the Aother gear train and the spindle.

lo. A machine tool comprising a rotatable and axially translatable spindle, driving means therefor, power transmission mechanism interposed between the driving means and the spindle comprising two gear trains, a jaw clutch between one of said gear trains and the spindle, a friction clutch between the other gear train and the spindle, and common control means for said clutches permitting engagement of only one at a time.

l1. A machine tool comprising a rotatable and axially translatable spindle, driving means therefor, power transmission mechanism interposed between the driving means and the spindle comprising two gear trains, a jaw clutch between one of said gear trains and the spindle, a friction clutch between the other gear train and the spindle, threaded means carried by the spindle, and stationary threaded means in engagement therewith.

l2. A machine tool comprising a rotatable and axially movable spindle, a threaded element car-` ried by the said spindle, a stationary threaded element in engagement therewith, a gear fixed to the spindle, a worm in engagement with the gear, and driving means for rotating said worm, a clutch between the worm and the driving means, and manual means for rotating the worm.

13. A machine tool comprising a base, a slide movably supported thereby, a screw for moving the slide upon the base having a threaded portion engaging a threaded element fixed to the slide, a bearing stationary with respect to the base supporting the screw, a thrust bearing between the screw and stationary bearing, a second thrust bearing on the opposite side of the stationary bearing, a sleeve Ibearing upon said last mentioned thrust bearing and surrounding a portion of the screw, a collar fixed to the screw within the sleeve, a compression spring interposed between the collar and sleeve, automatic means for moving the sleeve, and manual means for rotating the screw within the sleeve.

14. A machine tool comprising a base, a slide movably supported thereby, a screw for moving the slide upon the base having a threaded portion engaging a threaded element fixed to the slide, a bearing stationary with respect to the base supporting the screw, a thrust bearing between the screw and stationary bearing, a second thrust bearing on the opposite side of the stationary bea `ing, a sleeve bearing upon said last mentioned thrust bearing and surrounding a portion of the screw, a collar fixed to the screw within the sleeve, a compression spring interposed between the collar and sleeve, a cam connected to move said sleeve, and manual means for moving the screw within the sleeve.

l5. A machine tool comprising a rotatable work spindle, a tool holder, driving means for rotating the spindle about its axis, feed means actuated by the rotation of said spindle for movingy 1 1 the spindle and holder relatively in the direction of the axis of the spindle in two opposite directions, and independent feed means for moving the spindle and holder relatively in a direction transverse to the spindle axis. 16. A machine tool comprising two rotatable spindles, driving means connected to one of said spindles, independent driving means connected to the other said spindles, feed means actuated by said second driving means for feeding the spindle relatively in oneV direction, and control means permitting the second mentioned driving means to operate only while the first driving means is in operation.

17, A machine toolcomprising a rigid stationary base, a spindle carried by said base and ro'- tatable and axially movable with respect thereto, a threaded element detachably xed to said spindle, a second threaded element having a thread conjugate to that of the iirst mentioned element and in engagement therewith fixed relative to said base, a holder carried by said base and iixed in relation thereto, and driving means connected to said spindle, a Vrotatable spindle carried by the holder, and driving means for said last mentioned spindle independent of said first mentioned driving means.

CHARLES H. SCHURR. 

